Process and apparatus for producing crude oil from separate strata



Jan. 2, 1968 K. D. WHIPPLE 3,361,202

PROCESS AND APPARATUS FOR PRODUCING CRUDE OIL FROM SEPARATE STRATA Filed Aug. 5, 1965 sTEAM GENERATOR IN VEN TOR BY K.D. WHIPPLE A T TORNEKS" United States Patent 3,361,202 PROCESS AND APPARATUS FOR PRODUCING CRUDE OIL FROM SEPARATE STRATA Kenneth D. Whipple, Caracas, Venezuela, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Aug. 5, 1965, Ser. No. 477,414 7 Claims. (Cl. 16610) ABSTRACT OF THE DISCLOSURE This invention relates to a process and arrangement of apparatus for producing oil from a plurality of oil-bearing strata at diflferent levels in an oil field.

Some crude oils are so viscous that the viscosity must.

be reduced in order for the oil to be pumpable. One method of reducing the viscosity of a heavy crude oil is to raise the temperature thereof by heating same. Heating of viscous crudes is also beneficial in certain areas during cold periods when the oil tends to congeal in the lines serving the viscous oil wells in a field.

In some fields, several zones of highly viscous crudes at dilferent levels are amendable to simultaneous production providing the flow of the crudes can be maintained.

This invention is concerned with the simultaneous production of highly viscous crude oils from different level strata.

Accordingly, it is an object of the invention to provide a process and arrangement of apparatus for simultaneously producing viscous crude oil from separate strata at diiferent levels'in an oil field. A further object is to provide a process and apparatus for simultaneously heating a viscous crude in a production tubing carrying produced oil from one stratum while feeding heating fluid to a second viscous oil-bearing stratum penetrated by the same well. Another object is to heat a viscous crude in a tubing string leading from a producing stratum with steam passing to a second oil-bearing stratum at a higher or lower level thru a common well. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

A broad aspect of the invention comprises feeding steam thru a tubing string to a producing zone containing a viscous crude oil so as to produce oil therefrom and simultaneously heating a tubing string in the same well thru which is flowing a viscous crude oil from another producing zone, thereby rendering the viscous crude oil in the producing string more fluid so that higher pump eiliciency is obtained or less resistance to flow in the producing string is elfected.

It is effective to produce crude oil from an oil-bearing stratum by direct steam drive thru the stratum to one or more offset wells. It is also a recent practice to produce crude oil from an oil-bearing stratum with steam by the so-called hull and puff method wherein steam is injected into the stratum at a high temperature such as 600 to 800 F. for a substantial period thru an injection and production well until substantial steam pressure is built up in the surrounding stratum. Steam injection is terminated and after a substantial soaking period, the well is opened to production so that the stratum pressure forces the fluidized oil into the well from which it is 3,361,202 Patented Jan. 2, 1968 produced by pumping or by fluid pressure or other suitable method. The invention simultaneously heats the oil in a tubing string in the same well which is producing viscous oil at another level. This heating effect renders the pumping and production substantially easier. At the same time, the reduced viscosity of the heated oil permits it to flow thru gathering lines more readily, obviating the need for heating such lines above ground.

A more complete understanding of the invention may be had by reference to the accompanying schematic drawing of which FIGURE 1 is an elevation thru a section of stratum illustrating an arrangement of apparatus for performing the invention; and FIGURE 2 is a similar elevation illustrating a second mode of operation.

Referring to FIGURE 1, a well 10 penetrates an upper pay zone 12 and a lower pay zone 14. These pay zones are oil-bearing strata containing viscous crude oil and are separated by an impermeable barrier 16. A steam injection tubing string 18 extends to the area of stratum 14 and connects with a steam generator 20 thru line 22. A production line 23 connects with tubing string 18. A production tubing 24 provided with a pump 26 extends into stratum 12, the pump being operated by pumping rod 28. A production line 29 connects with tubing string 24. The wellbore is packed oft intermediate strata 12 and 14 by packer 30 and just above stratum 12 by packer 32. At least a portion of the area around tubing strings 1-8 and 24 above packer 32 may be filled with a heat exchange liquid 34, although substantial heat exchange between steam in tubing 18 and the oil in tubing 24 is effected by radiation and convection without the use of heat exchange liquid above packer 32.

An olfset well 36 also penetrates strata 12 and 14 and is provided with a pump 38 positioned on the lower end of tubing string 40 within lower stratum 14. Pump rod 42 operates the pump in conventional manner.

The arrangement illustrated in FIGURE 1 may be utilized in a huff and puff steam operation or it may be utilized in a direct steam drive thru lower pay zone 14 to one or more offset wells 36. In operating the hull? and puff steam method, the olfset wells 36 are closed in and steam is forced into the lower pay zone 14 from steam generator 20 thru tubing string 18 for a substantial period until a relatively high stratum pressure in zone 14 is established and substantial heating is effected in the oil-bearing stratum 14 around well 10'. After a substantial soaking period of one day to a week or more, the pressure in well 10 below packer 30' is released so that the oil, much of which has been cracked by the high temperature steam, flows into well 10 and is produced thru tubing 18 and production line 23. After production ceases, the cycle of steam injection, soaking, and production is repeated.

With a direct steam drive thru tubing string 18 and oil zone 14, the injection of steam is preferably continuous and the produced oil is recovered thru oifset Wells 36 which preferably surround well 10 in a ring pattern. When utilizing either direct steam drive or hulf and puff steam production, there is substantial heat exchange between the steam in tubing 18 and the oil in tubing 24 being produced from upper zone 12 by pumping. This heat exchange is facilitated by the use of heat exchange liquid such as oil, water, or other suitable liquid in the packed 01f zone above packer 32 surrounding tubing strings 18 and 24.

There is also heating benefit from the hot steam in the production tubing in well 10 when the steam drive or injection is applied to the upper zone 12 with viscous oil being produced by pumping from the lower zone 14.

In this application of the invention, the major portion of the production tubing from the lower zone is substantially heated by the steam in the tubing running to the upper zone.

FIGURE 2 illustrates a preferred method and apparatus arrangement for more effectively heating the production tubing extending to an oil-bearing zone with steam being injected into an upper oil-bearing zone. A well 40 penetrates upper zone 12 and lower zone 14 and is provided with a steam injection tubing 42 and a production tubing 44. A pump 46 on the lower end of tubing 44 is operated by rod 48. Production line 50 connects with tubing 44 for passage of oil to gathering lines. A similar production line 52 connects with tubing 42. Packers 54 and 56 pack off zone 12, a packer 54 providing an indirect heat exchange zone above zone 12 for heat exchange liquid illustrated at 58. In order to provide more effective heat exchange from the injected steam to the section of tubing 44 below packer 56, the section of tubing string 42 below zone 12 designated 60 is enclosed within a larger conduit 62 which is closed at the bottom end and open at the top end as at 64. A spider arrangement 66 is utilized to support and space conduit 62 from tubing 60. It is to be understood that the lower end of section 611 is open so that the steam flows out the lower end of this tubing and upwardly thru the annulus between tubing 60 and conduit 62. into zone 12 for either a direct drive or a huff and puff steam operation.

Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

I claim:

1. A process for producing heavy oil simultaneously from upper and lower oil-bearing strata comprising the steps of:

(1) injecting steam thru a first tubing in a first Well into said upper stratum to produce oil of reduced viscosity thru a well therein;

(2) producing oil from the lower stratum thru a second tubing in said first well; and

(3) passing the steam injected in step (1) thru conduit means extending to the lower stratum and then upwardly to the upper stratum before venting same to the well above a packed off zone intermediate said strata, thereby heating the oil in said second tubing with the steam injected in said first tubing so as to reduce the viscosity and increase the flowability of the oil in said second tubing.

2. The process of claim 1 wherein the steam injection in step (1) is intermittent and oil is produced thru said first tubing after each steam injection period and a steam soaking period with reduction of pressure in said first tubing.

3. The process of claim 1 wherein the steam injected in step (1) drives oil to an offset production well as the other well in step (1).

4. The process of claim 1 wherein said well above the upper stratum is packed off around both tubing strings and a heat exchange liquid is provided in the packed off section above said upper stratum to effect additional heating of the oil in the second tubing string of step (3).

5. Apparatus comprising in combination:

(1) a well penetrating an upper oil-bearing stratum and a lower oil-bearing stratum;

(2) a first tubing string having a pump on its lower end extending into the lower stratum of (1);

(3) a second tubing string for steam injection extending into the lower stratum;

(4) a packer packing off the well between said strata;

(5) steam generating means connected by conduit means with the second tubing string of (3); and

(6) conduit means connected with the lower end of the tubing string of (3) open above the packer of (4) to circulate steam in indirect heat exchange with fluids below said packer before delivering steam to the upper stratum.

6. The apparatus of claim 5 wherein the wellbore is packed off by a packer around both tubings adjacent the top of the upper stratum.

7. The apparatus of claim 6 including a heat exchange liquid in the packed off section above said upper stratum.

References Cited UNITED STATES PATENTS 3,105,545 10/1963 Prats 166-11 X 3,167,120 1/1965 Pryor 166-11 X 3,180,413 4/1965 Willman 166-11 3,273,640 9/1966 Huntington 166-11 X 3,294,167 12/1966 VOgel 166-11 CHARLES E. OCONNELL, Primary Examiner.

NILE C. BYERS, Assistant Examiner. 

